Digital content, including audio, video, images, multimedia, etc., is easy to copy and expensive to create. Thus, it is a great target for illegal distribution, defined as piracy. Currently, this piracy is occurring with audio, using MPEG-1 Layer 3 (MP3) bit-rate compression format and the Internet. The MP3 format is used by new artist who want their music freely distributed, as well as by people transforming CD audio into MP3 and possibly illegally distributing it on the Internet. Professional artists and record labels want to stop the second action while allowing the first, and even distribute new content in MP3.
The problem with robust embedded data based methods of protecting content in this insecure format is that they are computationally intense. The prior-art describes numerous examples of such methods using embedded data (a.k.a. watermarks or steganography) that require frequency transformations. Assuming a different watermark is required for each user, player, storage unit and/or content, distributors will need expensive equipment to protect the data and users will require expensive devices to render the content.
The problem with efficient embedded data methods used to protect the content in this insecure format is that they are easy to remove, even though they can be made robust to duplication, such as utility patent application Ser. No. 09/404,291 entitled “Method and apparatus for robust embedded data” submitted on Sep. 23, 1999 by Levy, included herein by reference. Removal of embedded data is not a problem if you require the content to contain the embedded data in order to be rendered, but this concept only works in a secure format. In other words, in an insecure format, if the embedded data that informs the rendering device that the content can or cannot be played is removed, the content can always be played. However, with a secure format, removal of the embedded data that informs the rendering device that the content can or cannot be played leaves the content useless since the device cannot render, such as decrypt, the content without this embedded authorization. For example, in MP3, an insecure format where there is a desire to freely distribute content without protection, the removal of the watermark creates useful pirated content.
Cryptology can also be used to secure the content. However, not only is this technique computationally intense since it requires many operations using a large number of bits, but also one can argue that the format has been changed since existing players cannot play the protected content.